In addition to Pat's excellent description - and maybe something for Howard's informative thread on CBs - is the fact that accreditation has significant 'costs'. Those CB organizations who establish and maintain an accreditation program for their certification services, are not 'fly-by-night organizations, simply because they must have the funding available. Each different standard requires a separate accreditation and the costs are not inconsiderable.
Those organizations who choose to 'dodge the bullet' and avoid gaining internationally recognized accreditation of its services, are pouring their revenues directly to profit, since they have no accreditation program burden. To be blunt, they make money from those who are ignorant of the situation!
And, to Pat's point, where does anyone who is new to certification, find this kind of information? What would YOU put into a Google search, if you had no clue?